Can you simplify this further?

Hi all,

Had an exam recently and I've got a nagging feeling about a particular question.

$\displaystyle f(x) = \frac{1-x^2}{1-x}$ and $\displaystyle g(t) = t^2$

Find $\displaystyle f(g(t))$ and simplify your answer.

So that results in

$\displaystyle \frac{1-(t^2)^2}{1-t^2}$

Which simplifies to

$\displaystyle \frac{1-t^4}{1-t^2}$

Is there any further simplification we can do? I can't see anything but I have this nagging feeling I'm missing something. Possibly further factorisation taking place considering 1 is also $\displaystyle 1^2$ etc leading to some cancelling out.

Did I miss anything?